Virtual Boundaries for Repositionable Arm Collision Avoidance
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Solution Overview
Problem
Existing collision avoidance systems for medical devices with repositionable arms, particularly in teleoperation, face challenges in predicting and preventing collisions in real-time due to delays in motion planning and reliance on actual collisions for feedback, leading to potential damage and poor operator experience.
Innovation Solution
The implementation of virtual boundaries around the repositionable arms, using high-fidelity CAD or kinematic models, which detect overlaps and apply feedback forces to prevent collisions before actual contact, enhancing haptic feedback and stability while allowing closer operation without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motion planning is used for collision avoidance, then collision prediction can be made, but real-time control is delayed due to operator teleoperation
Solution Approach 1:
The system performs preliminary collision detection by checking if the desired end effector position would cause a collision before executing the motion. The control system evaluates potential collisions in advance based on the operator's teleoperation commands and prevents harmful motions before they occur, resolving the contradiction between reliable collision avoidance and real-time response.
2Ease of operation
If collision detection is used instead of avoidance, then real-time feedback is provided, but actual collisions occur causing damage
Solution Approach 1:
The system applies preliminary anti-action by detecting desired positions that would lead to collision and preventing those motions before actual contact occurs. The control system rejects commands that would cause the repositionable arm to collide with other arms or equipment, providing real-time feedback to the operator while preventing damage to the sterile field and equipment.
3Device complexity
If large circumscribing volumes are used for collision detection, then collision prediction is simplified, but operational freedom is reduced
Solution Approach 1:
Instead of using large circumscribing volumes, the system applies local quality by performing collision detection at the specific end effector level. The control system evaluates collisions locally at the desired end effector position rather than using conservative large-volume approaches, maintaining simplicity while preserving full operational freedom of the repositionable arms.
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
A system and method of collision avoidance includes determining first positions of first joints of a first repositionable arm and second positions of second joints of a second repositionable arm. Distal ends of the first and second repositionable arms are configured to support first and second instruments, respectively. The system and method further include determining first and second virtual boundaries around the first and second repositionable arms, determining an overlap between the first and second virtual boundaries, determining an overlap force on the first repositionable arm due to the overlap, mapping the overlap force to virtual torques on the first joints proximal to the overlap, determining a tip force on a distal end of the first instrument, and applying the tip force as feedback on the first instrument.